红色荧光粉NaLa_4(SiO_4)_3F:Eu~(3+)的合成条件探讨

利用高温固相法合成NaLa4(SiO2)3F:Eu3+红色荧光粉,用X射线粉末衍射仪、扫描电镜和荧光分光光度计对荧光粉进行结构和性能表征,研究NaF用量、反应时间以及反应温度等条件对NaLa4(SiO4)3F:Eu3+发光性能的影响。结果表明,在395nm激发下荧光粉中的Eu3+离子主要发射5 D0→7F2(616nm)和5 D0→7 F1(590nm)跃迁;检测波长为615nm时,激发光谱由一个宽吸收带和若干吸收峰组成,其中在270nm附近的宽峰吸收带和394nm处的吸收峰最强,前者归属于O2--Eu3+离子间的电荷迁移吸收,后者归属于Eu3+离子的7 F0→5 L6跃迁吸收。NaF用量、反应时间以及反应温度对荧光粉的发光性能有一定的影响。     

水热法制备NaGd(WO_4)_2:Eu~(3+)发光材料

采用水热法,以十六烷基三甲基溴化铵(CTAB)为表面活性剂,合成了NaGd(WO4)2:Eu3+发光材料.采集XRD,SEM图谱来表征样品的晶型与形貌,利用激发光谱和发射光谱研究了材料的发光特性.结果表明,所制得的NaGd(WO4)2:Eu3+是由纳米棒组成的绒球状发光材料,球体直径为100nm,纳米棒长2～5μm.样品不仅可以被紫外光(266nm)激发,还能被近紫外光(393nm)和蓝光(464nm)有效激发,其主发射峰值位于614nm,为红色荧光成分,且当Eu3+掺杂物质的量分数为3%时,此发射峰达到最大,该发光粉可用于制造紫外光芯片激发的白光LED.     

CaSiO_3∶Eu~(3+)荧光粉的合成及光谱性质

利用高温固相法合成了CaSiO3∶Eu3+荧光粉,确定其最佳的合成条件为:烧结温度1200℃;烧结时间3h;助熔剂用量3%;激活剂的配比为2%(摩尔分数).对合成样品进行了荧光光谱分析,结果表明,该荧光粉的光谱中609nm处出现很强的发射峰,归属为Eu3+的5D0→7F2跃迁发射.     

红色荧光粉Ca_3B_2O_6:Eu~(3+)的制备及发光性能

采用高温固相法合成了Ca3B2O6:Eu3+红色荧光粉,并对其发光性质进行了研究.样品的激发光谱由位于220~350 nm的带状谱和350~500 nm的一系列窄带组成,这些窄带是由Eu3+的f-f跃迁引起的,光谱峰值分别为280,396和469 nm.它可以被近紫外光辐射二极管管芯产生的350~410 nm辐射有效激发.用396 nm激发得到样品的发射光谱,峰值位于578,590,610,618和650 nm,分别由Eu3+离子的5D4→7FJ(J=0,1,2,3)跃迁引起的.研究了Eu3+离子浓度和电荷补偿剂对发射光谱的影响.结果显示随着Eu3+浓度增加,发光强度逐渐增强,未发现浓度猝灭现象.掺入Li+,Na+,K+3种离子作为电荷补偿剂,均提高了样品的发光强度,其强度从大到小依次为I(Li+)I(Na+)I(K+),说明Li+是最佳的电荷补偿剂.     

CaSnO_3:Eu~(3+)荧光粉的制备及其发光性能研究

利用高温固相反应法制备CaSnO3:Eu3+发光体,采用X射线衍射(XRD)技术和荧光光谱等测试手段对样品进行研究.结果表明:Eu3+离子的掺杂未改变CaSnO3的晶体结构;Ca1-xEuxSnO3样品的发射以电偶极跃迁5D0-7F2为主,在紫外光照射下产生强的红光发射;Ca1-xEuxSnO3样品在240～340 nm范围内存在Eu3+-O2-电荷迁移吸收带,随着Eu3+掺杂浓度x的增加,吸收带峰位从276 nm红移到281 nm附近.     

Ca3(VO4)2:Eu3+,Bi3+荧光材料的结构及性能研究

采用燃烧法工艺合成了Ca3(VO4)2:Eu3+荧光粉,对其结构、形貌和发光性能进行了表征,该荧光材料颗粒形貌规则、均一、发射主峰位于615.0nm,是一种良好的红色荧光粉.     

红色荧光粉KGd(WO4)2:Sm3+的制备及发光性能

采用高温固相法合成KGd(WO4)2:Sm3+荧光粉,样品在近紫外区404nm光激发下发射出Sm3+的特征光谱.通过X射线粉末衍射、荧光光谱等对其进行了表征,并分析了其发光特性,结果表明:在KGd(WO4)2:Sm3+中Sm3+离子最佳的掺杂量为5%(摩尔分数);烧结温度为1 000℃、助熔剂H3BO3的浓度为2%(摩尔分数)时,样品的发光强度最强.     

LaOBr:Eu3+的制备及发光特性

采用固相合成法制备了Eu3+掺杂的LaOBr发光材料,研究了不同物质的量分数的Eu3+对发光性质的影响,其中Eu3+的物质的量分数为0.1%,0.2%,0.5%,1%.X线衍射图表明:所得样品为纯相的LaOBr.测量了不同物质的量分数的激发谱、发射谱及荧光寿命.通过对Eu3+衰减曲线的拟合,得到在相同Eu3+的物质的量分数下,从电荷迁移带跃迁到5 D0能级时间比5 D2能级跃迁到5 D0能级时间短,但从5 D0能级跃迁到基态能级的时间基本相同,说明Eu3+之间存在交叉弛豫现象.利用Judd-Oflet理论,从发射光谱获得了Eu3+的光学跃迁强度参数Ωλ(λ=2,4).     

Eu~(3+):ZnO_(1-x)S_x-2TiO_2-SiO_2发光材料的制备与发光性质

采用溶胶凝胶法与沉淀法,制备了Eu3+:ZnO1-xSx-2TiO2-SiO2发光材料,通过DTA-TG、IR、Raman、XRD、激发和发射光谱研究了材料的结构和发光性能.结果表明,样品在600℃退火处理后,体系基本达到稳定状态,主要以TiO2、ZnS的晶态形式存在;存在Ti-O-Ti、Si-O-Si、Ti-O-Si,Zn-S键,且Si-O-Si三维网络结构被破坏,这种结构的变化有利于Eu3+的掺杂和发光.激发和发射光谱测试表明,最佳激发波长为可见光465nm,最佳退火温度为600℃,Eu3+最佳掺杂量为6.0%.同时证明Eu3+:ZnO1-xSx-2TiO2-SiO2材料的发光性能比Eu3+:ZnO-2TiO2-SiO2的好,说明体系中硫的引入改善了材料的发光性能.     

蓝色荧光粉Ca_2B_5O_9Cl∶Eu~(2+)的甘氨酸燃烧法合成及其发光性能

为探索LED用荧光粉Ca2B5O9Cl∶Eu2+的合成和发光性能,首次采用甘氨酸燃烧法于750℃下合成了Ca2B5O9Cl∶Eu2+蓝色荧光粉,研究了不同摩尔分数(x)的甘氨酸与硝酸溶液中铕离子的最佳反应配比(n甘氨酸∶nEu2+).用XRD、荧光磷光分光光度计对该荧光粉的物相及发光性能进行了表征和研究,结果表明:在340 nm激发下可得到434 nm处蓝光发射峰,属于Eu2+典型的4f65d1→4f7的跃迁所致.     

柠檬酸络合溶胶-凝胶法制备稀土掺杂蓝色荧光粉

以柠檬酸为络合剂,用溶胶-凝胶法合成了稀土元素掺杂的蓝光荧光粉的BaMgAl10O17:Eu2+.对制备过程进行了研究,并通过红外光谱、热重-差示扫描量热谱和X射线衍射等手段,对干凝胶的构成、热分解特性和BaMgAl10O17:Eu的结晶行为等进行了分析讨论.荧光粉的激发光谱和发射光谱等发光特性的考察结果表明:1 200℃灼烧,可以得到较好的BaMgAl10O17:Eu晶相,其比用高温固相法合成低200℃以上.合成的荧光粉在紫外激发下,荧光粉的最大激发波长为340 nm,最大发射波长454 nm;真空紫外激发的最大激发波长为160 nm,最大发射波长约453 nm.     

Synthesis and luminescence properties of Ca2SiO4-based red phosphors with Sm3+ doping for white LEDs

Sm³⁺-activated Ca₂SiO₄ red phosphors were prepared by the conventional high-temperature solid-state reaction method, and the effects of sodium (Na⁺) and samarium (Sm³⁺) ions doping concentrations on their crystal structure and luminescent properties were investigated by X-ray diffraction (XRD) and fluorescent spectrofluorometer. XRD patterns demonstrate that a well-crystalline structure forms in the phosphors when they are treated by calcination at 1200°C for 4 h, and the excitation spectra exhibit good absorption in the range between 350 and 420 nm. Under the irradiation of 405 nm near-ultraviolet (NUV) light, the spectra of the phosphors show a main emission peak at 601 nm attributed to the ⁴G_5/2??⁶H_7/2 transition of Sm³⁺ ions, and its intensity is greatly influenced by the concentrations of Sm³⁺ and Na₂CO₃. When the concentrations of Sm³⁺ ions and Na₂CO₃ are 2mol% and 6mol%, respectively, the optimal emission intensity can be obtained. From strong absorption in the near ultraviolet zone, the Na_0.06Sm_0.02Ca_1.92SiO₄ phosphor is a promising red-emitting phosphor for white light emitting diodes (W-LEDs).     

Potential red-emitting phosphor GdNbO4:Eu3+,Bi3+ for near-UV white light emitting diodes

A red-emitting phosphor GdNbO₄:Eu³⁺,Bi³⁺ was prepared by a high temperature solid-state reaction technique. The phosphor was characterized by X-ray diffraction (XRD), particle size analyzer and fluorescence spectrometer. The single phase of GdNbO₄:Eu³⁺,Bi³⁺ was obtained at 1150°C and the average particle diameter was about 2.30 ??m. Excitation and emission spectra reveal that the phosphor can be efficiently excited by ultraviolet (UV) light (394 nm) and emit the strong red light of 612 nm due to the Eu³⁺ transition of ⁵D₀??⁷F₂. The optimum content of Eu³⁺ doped in the phosphor GdNbO₄:Eu³⁺ is 20mol%. The phosphor Gd_0.80NbO₄:0.20Eu³⁺,0.03Bi³⁺ shows much stronger photoluminescence intensity and better chromaticity coordinates (x=0.642, 0.352) than GdNbO₄:Eu³⁺. It is confirmed that Gd_0.80NbO₄:0.20Eu³⁺,0.03Bi³⁺ is a potential candidate for near-UV chip-based white light emitting diodes.     

白光LED用高亮度橙色高温相Ca3SiO4Cl2:Eu2+荧光粉

 采用高温固相法合成了高亮度橙色高温相Ca_2.99Eu_0.01SiO₄Cl₂荧光粉,进行了发光特性表征并探索了其在LED上的应用。Eu²⁺离子在Ca₃SiO₄Cl₂基质中可被300~450 nm光有效激发发出橙黄光,发射光谱是Eu²⁺离子的特征4f⁶5d¹→4f⁷跃迁发射带。测量得到的Eu²⁺离子的荧光寿命为微秒量级,分别是 τ₁＝1.53 μs和τ₂＝7.29 μs。用该荧光粉制备了395nm近紫外芯片基和460 nm蓝光芯片基发光二极管,并测试了它们的发光性能,表明高温相Ca_2.99Eu_0.01SiO₄Cl₂荧光粉适合于用作白光LED的红黄色组分。     

Down-conversion characteristics of Eu3+ doped M2Y2Si2O9 (M = Ba,Ca, Mg and Sr) nanomaterials for innovative solar panels

Down-conversion properties of Eu³⁺ doped M₂Y₂Si₂O₉ (M = Ba, Ca, Mg, Sr) phosphors have been investigated in detail. These phosphors were synthesized via the simple, fast and cost-effective sol-gel technique at a temperature of 950 °C. Color coordinates and emission color can be altered by the varying concentration of dopant ion in Ca₂Y₂Si₂O₉ phosphor. Optimum luminescence intensity was obtained when doping 0.03 mol of Eu³⁺ ion. Using the excitation wavelength of 395 nm, these silicates showed strong red color, pure and sharp spectral peaks in visible region due to ⁵D₀→⁷F_1-3 transitions of Eu³⁺ present in the lattice. Effect of reaction temperature on luminescence was also analyzed for these phosphors. The sharp peaks in the X-ray diffraction pattern indicated the high crystallinity of prepared phosphors. Ca₂Y₂Si₂O₉ has shown an orthorhombic crystal structure. The FTIR results confirmed the metal-oxygen vibrational modes available in the range of 400–1600 cm^?1. Transmission electron microscopy images have revealed that the variation of alkaline earth metal provided a very different crystal structure. Excellent down conversion response of these phosphor materials can provide a great significance in the application of the coming solar devices.     

不同离子对氧化锌晶体形貌的影响

以不同Zn盐Zn(CH3COO)2.2H2O,ZnCl2,ZnSO4.7H2O,Zn(NO3)2.6H2O与不同碱NaOH,KOH为原料,制得Zn(OH)42-前驱溶液,使之在水热环境下分解,生成ZnO晶体.产物通过全自动X射线衍射仪(XRD)进行物相分析,扫描电子显微镜(SEM)观测ZnO晶体的形貌和大小.170℃,溶液中的阴离子CH3COO-,SO42-,NO3-,Cl-分别与Na+构成干扰离子对,伴随着晶体生长12 h,晶体成长为片球集状、极性生长明显的花状、极性生长不明显的花状、小尺寸花状ZnO晶体;140℃,溶液中阳离子Na+,K+分别与CH3COO-作为离子对,干扰晶体生长,12 ...     

Preparation and luminescence characteristics of Sr3SiO5：Eu^2＋ phosphor for white LED

The Sr3SiO5：Eu^2＋ phosphor was synthesized by high temperature solid-state reaction. The emission spectrum of Sr3SiO5：Eu^2＋ shows two bands centered at 487 and 575 nm, which well agree with the theoretic values of emission spectrum. The excitation spectrum for 575 nm emission center has several excitation bands at 365, 418, 458 and 473 nm. And the results show that the emission spectrum of Sr3SiO5：Eu^2＋ is influenced by the Eu^2＋ concentration. The relative emission spectra of the white-emitting InGaN-based YAG：Ce^3＋ LED and Sr3SiO5：Eu^2＋ LED were investigated. The results show that the color development of InGaN-based Sr3SiO5：Eu^2＋ is better than that of InGaN-based YAG：Ce^3＋, and the CIE chromaticity of InGaN-based Sr3SiO5：Eu^2＋ is （x=0.348, y=0.326）.     

Study the effects of metallic ions on the combination of DNA and histones with molecular combing technique

The effects of monovalent (Na^ , K^ ) and divalent (Mg^2 , Ca^2 , Mn^2 ) ions on the interaction between DNA and histone are studied using the molecular combing technique. λ-DNA molecules and DNA-histone complexes incubated with metal cations (Na^ , K^ , Mg^2 , Ca^2 , Mn^2 ) are stretched on hydrophobic surfaces, and directly observed by fluorescence microscopy. The results indicate that when these cations are added into the DNA solution, the fluorescence intensities of the stained DNA are reduced differently. The monovalent cations (Na^ , K^ ) inhibit binding of histone to DNA. The divalent cations (Mg^2 , Ca^2 , Mn^2 ) enhance significantly the binding of histone to DNA and the binding of the DNA-histone complex to the hydrophobic surface. Mn^2 also induces condensation and aggregation of the DNA- histone complex.     

Photoluminescence and cathodoluminescence properties of CaLaGa<Subscript>3</Subscript>O<Subscript>7</Subscript>:Eu<Superscript>3+</Superscript> phosphors

The CaLaGa₃O₇:Eu³⁺ phosphor was prepared by a chemical co-precipitation method. Field emission scanning electron microscopy (FE-SEM), laser particle size analysis, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence (CL) spectra were utilized to characterize the synthesized phosphor. The results revealed that the phosphor was composed of microspheres with a slight agglomerate phenomenon and was spherically shaped. The average grain size was about 1.0 μm. Eu³⁺ ions, as luminescent centers, substituted La³⁺ ions into the single crystal lattice of CaLaGa₃O₇ with the sites of C_s. Although the CL spectrum was greatly different from the PL spectrum, it had the strongest red emission corresponding to the ⁵D₀ →⁷F₂ transition of Eu³⁺. Under the excitation of UV light (287 nm) and electron beams (1.0–7.0 kV), the chromaticity coordinates of the phosphor were found to be in the nearly red and orange light regions, respectively.     

免烧成硼酸铝-碳化硅耐火材料的性能

以碳化硅为主要原料,分别以酚醛树脂、氧化铝和氧化硼粉体作为常温和高温结合剂,研究了免烧成硼酸铝-碳化硅耐火材料的体积密度、抗折强度和抗热震性.结果表明:当酚醛树脂的质量分数为5%时,耐火材料的体积密度和抗折强度分别为266g·cm-3和13~21MPa;在960℃烧结之后,主要物相为SiC,Al2O3,Al4B2O9;当高温结合剂的质量分数为75%时材料的体积密度最大,为255g·cm-3;当高温结合剂的质量分数为125%时,材料的抗折强度最大,为19MPa;经过5次高温热震后,高温结合剂的质量分数为75%时材料抗热震性较好,强度损失率为25%.